Production of butadiene



oct., 9,1945. A E', ORCH 2,386,324'

PRODUCTION OF BUTADIENE y Filed April is, 1943 CoA/anwb? 1 Cowan/.SER

0 I COLLE 'EPARA 70/2 46 v f5 47 f3 4.3 @anzi/vf Gli/cm ATTORNEYS vcol by splitting oil water in accordance Patented Oct. 9, 1945 UNITED As'rsrl-:s APATENT OFFICE PRODUCTION F BU'I'ADIENE- Arthur E. Lorch, Tenaily, N. J., asslgnor toAir' Reduction Company, Incorporated, New York,

N. Y., a corporation of ANew York Application April 16, 1943, Serial No. 483,343

1Clalm.

Thisinvention relatesto the production of 1,3- butadiene from 1,3-butylene glycol and particularly to an improved method affording a commercially practicable procedure for economical recovery of the desired product.

1,3-butadiene is derived from 1,3-butylene glywith the following reaction:

There have been suggestioniI heretofore for de-Y hydration of 1,3-butylene glycol in the vapor phase by contact with a suitable catalyst, usually a phosphate of calcium or sodium, in the presence of free phosphoric acid. The latter, at elevated temperatures, is extremely active, and consequently the catalyst masses are rapidly disintegrated under operating conditions. Since it is necessary to afford space for the vapor' to flow through the reactor and moreover to provide maximum surface contact between the catalyst and the vapor, disintegration ofthe catalyst mass rapidly reduces the eiilciency of, and finally prevents continued operation because of the packing of the disintegrated material into a practically imperviouslayer in the reactor. A

It isthe object of the present invention to prepare 1,3-butadiene from -1,3butylene glycol in-a simple, economical and eicient procedure suitable for commercial application.

Another object of the invention`is the provision of a method which ensures prolonged activity of the catalyst mass and particularly avoidance of disintegration thereof, thus aiording continued eiliciency in operation. x

Other objects and advantages of the invention will be apparent as it isbetter lunderstood by reference to the following specification-and the accompanying drawing, which illustrates diagrammatically an apparatus suitable for the practice of the invention.

drawal of the gaseous products from which the butadiene can be readily separated The remainder of the gaseous products can be recovered and returned for further treatment.

The catalyst body is'maintained preferably at -a temperature rangingfrom 220 to 400 C., the

most effective range for the catalyst hereinafter described being approximately 280 to 320 'C.

The temperature may be maintained by eircu' lating a suitable heating medium such for example as a mixture of diphenyl and diphenyl oxide known as Dowtherm about the catalyst As'the catalyst, I prefer to employ ammonium phosphate. The term ammonium phosphate is employed as a general designation of the tri.; di, and mono ammonium phosphates or mixtures of these salts. It is employed also to include decomposition products of these phosphates which are subject to modification when subjected to temperatures such as those employed .in the method. The precise composition of the resultant salt or salts in the catalyst mass at the temperature maintained cannot be determined accurately.

Any'of the phosphates mentioned, or the result- A ing products, are active catalysts for the reaction.

I have discovered that butadiene can be prov Y duced advantageously by passingv 1,3-butylene glycol inthe vapor phase over an improved catalyst mass which is adapted to withstand the disintegrating effect of free phosphoric acid. Such a catalyst mass can be prepared readily and utilized in accordance with the present invention to materially prolong the period of eillcient ac tivity of the catalyst.

The procedure depends-upon the introduction of 1,3-butylene glycol inthe vapor phase to a body of the catalyst which is maintained at a. suitable temperature and the continuous with- I have found that ammonium phosphate 4is markedly superior to the phosphate catalysts which have been mentioned in the literature concerning dehydration of 1,3-butylene glycol.

In order to attain the most effective use of "ammonium phosphate as a catalyst for the reaction, it is desirable to mount it on. a suitable support. Most of the supports commonly suggested 'for use in the preparation of catalyst bodies are useless for the purpose of the present invention, because they do not withstand the disintegrating eiect of free phosphoric acid which Y is inevitably present at the temperature employed. I have discovered, however, that silica affords a satisfactory support for "ammonium phosphate" in 'catalyst masses to be employed for the purpose of the present invention. The preferred forms of silica which I have employed successfully for the purpose areal calcined diatomaceous earth con- Y -sisting essentially of silica and generally known pipe l5.

'I'he gaseous products of the reaction areV withmonlum phosphate. The lexcess liquid may be drained away and the wetted support may then be dried. Alternatively. a solution of ammonium phospha may be added to the supporting material and the mass may be dried while it is stirred to maintain uniformity. Whatever procedure is adopted, the supporting material carrying the4 ammonium phosphate may be formed into pellets in accordance with the usual method. The pellets may be of any desired size adapted to aii'ord maximum, surface contact with Vthe necessary interstices through which the vapor may readily pass. n

The proportion of the ammonium phosphate. in the catalyst body may be varied over wide limits. It will depend in part upon the degree and type of porosity of the supporting material as weil as the size of the supported pieces. Satisfactory catalysts have been prepared covering the range of to 60% ammonium phosphate. The size of the individual pieces oi catalyst body can be varied within wide limits to secure the optimum contact with the reactant gases.

As the result of dehydration of the 1,3-butylene glycol, butadieneis produced admixed with unreacted and partially reacted glycol. By passing the vapors through a suitable condenser at about 100 C., the unreacted glycol can be liquefied,

separated and returned for further treatment.

The partially reacted glycol or butenol with water and the butadiene pass the condenser. The putaand returned for further treatment with the catalyst. Water is withdrawn at the bottom oi the column.

The procedure will be readily understood by reference to the drawing, it being understood and 24. The condensate is delivered to a collector 25 having a sight lglass 26 wherebythe level of the liquidtherein may be observed. Butadiene escapes through a pipe 21, is preferably compressed by a compressor 28, and is delivered to a condenser 29. Cooling water may be introduced through a' pipe 30 and withdrawn through a pipe 3|. The butadiene in the liquid phase may be withdrawn .through` a pipe 32 and delivered to any suitable storage receptacle.

The liquid from the collector 25 is delivered through a pipe 33 controlled by a valve34 to a separator 35 having a sight glass 36 permitting observation of the liquid levels. The liquid separates into two layers. The upper oily layer, containing part of the butenol, may be withdrawn through a pipe 3l and delivered by a pump 38 and pipe 39 to the pipe l0, where it mingles with the glycol introduced to the vaporizer Il.

The liquid in the bottom of the separator 35 is withdrawn through a pipe 40 `controlled by a valve 4I and is delivered by a pump 42 and pipe 43 to a rectifier 44 having the usual plates or trays 45. The bottom ofthe rectifier is supplied with heat by means of a coil 46 through which any suitable heating medium may circulate. The rectication results in the separation of water at the bottom which may be withdrawn through the pipe 41 controlled by a valve 48. The'a'zeotrope of partially reacted glycol or butenol and water escapes through a pipe 49 at the top of the rectiiie'r and be readily understood that the apparatus described is merely illustrative of suitable equipment for the purpose. The reactor 5 may be a tubular chamber of suitable material surrounded by a heating jacket 6to which the heating fluid is introduced through a pipe l and withdrawn through a pipe 8. The catalyst 9 is disposed within the chamber 5in the esult. 1,3-butylene glycol is supplied through a pipe I0 to a vaporizer Il which may be heated, for

example. by passage of a suitable liquid such as Dowtherm" through a jacket l2. The heating liquid is introducedthrough a pipe i3 and withdrawn through a pipe I4. `'The glycol is thus .vporized anddelivered to the chamber 5 by a.

drawn through a pipe I5 and delivered to a condenser `I'IsuppIied with cooling liquid such as water through a pipe I0. The water escapes througha pipe I9. The condensate, Vconsisting of unreacted glycol, is delivered .by a pipe 20 to the pipe Il and vaporizer Il.

The remaining vapors are'delivered by a pipe 2| to a condenser 22 through which a cooling liquid such as water is circulated by pipes 23 form of pellets of suitable size to eiect the desired at a rate of 25-35 grams per hour. After 56 days is delivered to a-condensei 50. Cooling water may be introduced through the pipe 5I and withdrawn through a pipe 52. The condensed azeotrope is delivered through a. pipe 53, pump 54 and pipe 55 to the pipe l0, and is thus returned for further reaction in contact with the catalyst.

The practical operation of the invention will from the following examples:

Exemple I A catalyst was prepared by soaking 4-8 mesh Celite V in a saturated aqueous solution of diammonium phosphate. The mass was drained and dried at 100 C. It was placed in the reactor and heated to a temperature of 3D0-320 C. A 50% `aqueous solution of 1,3-butylene glycol was vaporized and passed through the catalyst. The butadiene was separated as hereinbefore described. After 30 days of operation, the catalyst` In an operation similar to that described in Example I, I employed a catalyst composed of about 15% liii-ammonium phosphate mounted on feldspar-bonded silica of approximately 4-8 mesh size. was vaporlzed and delivered to the catalyst mass of operation, the catalyst showed oniyabout 50% disintegration. Yields'. were satisfactory.

The foregoing examples are merely illustrative of various modications which can be made in the operation of the invention. Two elements are, however, important; the use of ammonium phospha as the active catalytic material and the use of a support consisting essentially of silica. The use or these elements of the invention ensures satisfactory. yields andicontinued catalytic activity over long periods of time. The invention is limited, therefore, only with respect to the aqueous 1,3-butylene glycol solution essential conditions of operation as hereinbeiore set forth.- l

Various changes may be made in the apparatus employed and in the ldetails of procedure without 'I'hemethod of dehydratlng 1,3-buty1ene glycol to produce 1,3-butadlene which comprises passing the glycol in the v apor phase over a catalyst body consistingv of ammonium phosphate on an depating from the invention of sacrificing the 5 inert support composed essentially o! silica in the advantages thereof.l I claim:

form oi' calcined diatomaceous earth. ARTHUR E. LORCHv 

